Look at the thread that started this all 
Works! Had to dig deep in the /dev section to find all parameters properly, but finally it did it. Thanks again! One more thing to mention: the Previous/Next Track button now isn’t working as expected when playing from the Playlists: it starts to play some songs randomly, not really the previous/next one in the Playlist. Is something I could do about to get the proper functionality back?
Edit: It was only, that the Randomizer option was turned on somehow. I switched it off and now everything seams normal.